1. Field of the Invention
The invention relates to buffer management, and more particularly to managing the transfer of data from a host computer to a recordable disk in a disk drive operating on the host computer using a buffer.
2. Description of the Related Art
A disk drive typically includes one or more magnetic disks. Each disk typically has a number of concentric rings or tracks on which data is stored. The tracks themselves may be divided into sectors, which are the smallest accessible data units. A positioning head above the appropriate track accesses a sector. An index pulse typically identifies the first sector of a track. The start of each sector is identified with a sector pulse. Typically, the disk drive waits until a desired sector rotates beneath the head before proceeding for a read or write operation. Data is accessed serially, one bit at a time and typically, each disk has its own read/write head.
The disk drive is connected to a disk controller, which is the circuit that allows a host computer to communicate with the disk drive. The disk controller performs numerous functions, for example, converting digital data to analog head signals, disk formatting, error checking and fixing, logical to physical address mapping and data buffering. To perform the various functions for transferring data, the disk controller includes numerous components.
Typically, the data buffering function is used to transfer data between the host computer and the disk. Data buffering is needed because the speed at which the disk drive can supply data or accept data from the host is different than the speed at which the host can correspondingly read or supply data. Conventional systems include a buffer memory that is coupled to the disk controller. The buffer memory temporarily stores data that is being read from or written to the disk drive.
Conventionally, when data is read from the disk drive, a host system sends a read command to the disk controller, which stores the read command into the buffer memory. Data is read from the disk drive and stored in the buffer memory, and transferred from the buffer memory to the host system.
In this regard, different buffer management techniques have been used to manage the access of data to and from the buffer. What is desired is an efficient management of data transfer from a host computer to a recordable disk drive, using a memory buffer.